Module: Diff::LCS::Ldiff

Defined in:
lib/diff/lcs/ldiff.rb

Overview

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Constant Summary collapse 

<<-COPYRIGHT
ldiff #{Diff::LCS::VERSION}
Copyright 2004-2019 Austin Ziegler

Part of Diff::LCS.
https://github.com/halostatue/diff-lcs

This program is free software. It may be redistributed and/or modified under
the terms of the GPL version 2 (or later), the Perl Artistic licence, or the
MIT licence.
COPYRIGHT

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.data_new ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 26

def data_new
  @data_new
end

.data_old ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 26

def data_old
  @data_old
end

.file_new ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 25

def file_new
  @file_new
end

.file_old ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 25

def file_old
  @file_old
end

.format ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 24

def format
  @format
end

.lines ⇒ Object (readonly)

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# File 'lib/diff/lcs/ldiff.rb', line 24

def lines
  @lines
end

Class Method Details

.run(args, _input = $stdin, output = $stdout, error = $stderr) ⇒ Object

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# File 'lib/diff/lcs/ldiff.rb', line 28

def run(args, _input = $stdin, output = $stdout, error = $stderr) # :nodoc:
  @binary = nil

  args.options do |o|
    o.banner = "Usage: #{File.basename($0)} [options] oldfile newfile"
    o.separator ""
    o.on(
      "-c", "-C", "--context [LINES]", Integer,
      "Displays a context diff with LINES lines", "of context. Default 3 lines."
    ) do |ctx|
      @format = :context
      @lines = ctx || 3
    end
    o.on(
      "-u", "-U", "--unified [LINES]", Integer,
      "Displays a unified diff with LINES lines", "of context. Default 3 lines."
    ) do |ctx|
      @format = :unified
      @lines = ctx || 3
    end
    o.on("-e", "Creates an 'ed' script to change", "oldfile to newfile.") do |_ctx|
      @format = :ed
    end
    o.on("-f", "Creates an 'ed' script to change", "oldfile to newfile in reverse order.") do |_ctx|
      @format = :reverse_ed
    end
    o.on(
      "-a", "--text",
      "Treat the files as text and compare them", "line-by-line, even if they do not seem", "to be text."
    ) do |_txt|
      @binary = false
    end
    o.on("--binary", "Treats the files as binary.") do |_bin|
      @binary = true
    end
    o.on("-q", "--brief", "Report only whether or not the files", "differ, not the details.") do |_ctx|
      @format = :report
    end
    o.on_tail("--help", "Shows this text.") do
      error << o
      return 0
    end
    o.on_tail("--version", "Shows the version of Diff::LCS.") do
      error << Diff::LCS::Ldiff::BANNER
      return 0
    end
    o.on_tail ""
    o.on_tail 'By default, runs produces an "old-style" diff, with output like UNIX diff.'
    o.parse!
  end

  unless args.size == 2
    error << args.options
    return 127
  end

  # Defaults are for old-style diff
  @format ||= :old
  @lines ||= 0

  file_old, file_new = *ARGV

  case @format
  when :context
    char_old = "*" * 3
    char_new = "-" * 3
  when :unified
    char_old = "-" * 3
    char_new = "+" * 3
  end

  # After we've read up to a certain point in each file, the number of
  # items we've read from each file will differ by FLD (could be 0).
  file_length_difference = 0

  data_old = File.read(file_old)
  data_new = File.read(file_new)

  # Test binary status
  if @binary.nil?
    old_txt = data_old[0, 4096].scan(/\0/).empty?
    new_txt = data_new[0, 4096].scan(/\0/).empty?
    @binary = !old_txt || !new_txt
  end

  unless @binary
    data_old = data_old.lines.to_a
    data_new = data_new.lines.to_a
  end

  # diff yields lots of pieces, each of which is basically a Block object
  if @binary
    diffs = (data_old == data_new)
  else
    diffs = Diff::LCS.diff(data_old, data_new)
    diffs = nil if diffs.empty?
  end

  return 0 unless diffs

  if @format == :report
    output << "Files #{file_old} and #{file_new} differ\n"
    return 1
  end

  if (@format == :unified) || (@format == :context)
    ft = File.stat(file_old).mtime.localtime.strftime("%Y-%m-%d %H:%M:%S.000000000 %z")
    output << "#{char_old} #{file_old}\t#{ft}\n"
    ft = File.stat(file_new).mtime.localtime.strftime("%Y-%m-%d %H:%M:%S.000000000 %z")
    output << "#{char_new} #{file_new}\t#{ft}\n"
  end

  # Loop over hunks. If a hunk overlaps with the last hunk, join them.
  # Otherwise, print out the old one.
  oldhunk = hunk = nil

  if @format == :ed
    real_output = output
    output = []
  end

  diffs.each do |piece|
    begin # rubocop:disable Style/RedundantBegin
      hunk = Diff::LCS::Hunk.new(data_old, data_new, piece, @lines, file_length_difference)
      file_length_difference = hunk.file_length_difference

      next unless oldhunk
      next if @lines.positive? && hunk.merge(oldhunk)

      output << oldhunk.diff(@format)
      output << "\n" if @format == :unified
    ensure
      oldhunk = hunk
    end
  end

  last = oldhunk.diff(@format, true)
  last << "\n" if last.respond_to?(:end_with?) && !last.end_with?("\n")

  output << last

  output.reverse_each { |e| real_output << e.diff(:ed_finish) } if @format == :ed

  1
end